While this feature is included with some cloud phone systems, it can also be integrated with an existing business voicemail service. In this case, the user directs his/her voicemail-to-email feature to send all voicemails to the third party transcription service. The third party service then transcribes the voicemails and sends the user an email or SMS with the transcription.
The problem there is that VoIP traffic is much more sensitive to network bumps and potholes than most general office traffic. That translates to garbled conversations, difficulty connecting over Wi-Fi, or (worst case) dropped and lost calls. If your business is small and your network is essentially contained in one or two wireless routers, then your configuration and testing headaches might be fairly easy (though still there). For medium and larger networks, these tasks can be complex and time-consuming, which translates into added cost in terms of man-hours.

Cell phone voicemail greetings are generally more personal and casual than office phones. Consider a greeting like “Hello, you’ve reached [your name]’s cell phone. I can’t take your call at the moment, but if you leave a brief message, I’ll get back to you as quickly as possible.”
While service fees can vary tremendously based on the organizational need, we can't provide a ballpark figure. These services will have to be evaluated by a potential provider who can then deliver a quote. But we can tell you which factors will impact the service fee. Those factors include: Number of Users Number of Sites Phone Model Add-On Phone Services Layer of Redundancy Type of System Selected Required Training Annual Maintenance Requirements